Explosive actuated switch



March 22, 1960 A. E. BLOMGREN 2,929,892

EXPLOSIVE CTUATED SWITCH Filed Nov. 19, 1957 mvENToR.

v AXEL Evt-QT BLoMGpE/v 4/ BY FIGA- M7/Mm United States Patent() 2,929,892 ExPLosrvE VAcruArEn swrrcn Axel Evert Blomgren, Kensington, Conn., assgnor to Raymond Engineering Laboratory, Inc., Middletown, Conn., a corporation of Connecticut Application November 19, 1957, Serial No. 697,463

2 Claims. (Cl. 200-82) This invention relates to electrical switches and more particularly to a novel and improved fast acting switch of the explosive actuated type.

It is an object of the invention to provide a novel and improved electrical switch of the explosive actuated type which is characterized by extremely fast action and which may be utilized to open and/or close electrical circuits with minimum time delay responsive to an electrical signal.

lt is further the object of this invention to provide a switch as described which will provide reliable operation even after prolonged storage in environments having wide ranges of temperature and relative humidity, which is rugged so as to withstand high forces due to vibration or acceleration, and which is of relatively small size and relatively simple and economical to manufacture and assemble.

Our objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. l is a side elevational view of an explosive actuated switch constructed in accordance with the invention;

Fig. 2 is an end view of the switch of Fig. l;

Fig. 3 is an enlarged fragmentary cross sectional View substantially along the line 3 3 of Fig. 2; and

Fig. 4 is a cross sectional view along the line 4--4 of Fig. 3.

Referring to the drawings, an explosive switch embodying the invention is contained in a cylindrical metal tube or housing preferably formed of non-corrodible material such as brass. One end of the housing may be threaded as indicated at 12 to facilitate mounting of the switch in a panel or the like. The left hand end of the tube 10 as viewed in Fig. l is closed by a plug 14 preferably molded of a non-metallic material such as a hard plastic. The plug 14 has a tapered nose 16 which extends outwardly through the opening formed by the lip 18 and is sealed thereto by a layer of plastic filler material 20. A pair of twisted electrical wires 22 are imbedded in the plug 14 with one end of the wires extending outwardly from the plug and the other end being connected to a primer cap 24 containing the usual explosive primer charge such as lead styphnate, the cap being situated on the inner face of the plug.

The inner end of plug 14 is of reduced diameter and is seated in the end of a cylindrical sleeve or bushing 26` formed of non-metallic material such as nylon or the like forming an explosion chamber within the housing 10. Slidable in the sleeve or bushing 26 is a plunger 28 in the form of a disc having a relatively tight lit with the inner surface of the sleeve 26. Located on the right hand face of plunger 28 as viewed in Fig. 1 is a silver disc 30.

2,929,892 Patented Mar. 22, 1960 ICC The right hand end of the sleeve 26 is closed by a fiber disc 32 which is seated in the annular groove 34. Extending diametrically through the sleeve 26 is a copper wire 36 which is preferably flattened as at 38 to structurally weaken this section of the wire and render it more frangible. The wire 36 extends outwardly through aligned notches 40, 41, in the sleeve 26 and disc 32 and thence through apertures 42 in a ber disc 44 and finally outwardly of its housing through varnished fiber glass tubing 46 set in fungus proof varnish in a brass disc or plug 48. The plug 48 closes the right hand end of the housing 10 (as viewed in Fig. 1) and is held in place by the peened over edge 50 of the housing 10.

Two additional wires 52 extend into the housing through the plug 48 and fiber disc 44 and are similarly encased in varnished fiber glass tubing 54 cemented in apertures in the plug 48. Each of the wires 52 at their inner ends are looped through apertures 56 in the fiber disc 32 to form spaced apart contacts 5S on the inner face of the disc 32.

ln order to actuate the switch, all that is required is the energizing of the primer cap wires 22 which ignites the primer cap 24 and drives the plunger 2S to the right (as viewed in Fig. l) thus causing severance of the wire 36 and bridging of the contacts 5S by the silver disc 30. Thus any electrical circuit connected to the wire 36 is opened and any electrical circuit connected to Wires 52 is opened. ln switches of small size, no explosive in addition to the primer cap is required. The plunger 2S is initially placed with the silver tace disc 30 abutting the wire 36 so that a minimum of movement is required to sever the wire 36 and the distance of the contacts 58 from the wire 36 is relatively short so that bridging of the contacts 58 will occur rapidly thereafter.

A switch constructed as described in accordance with the invention will provide very fast action. For example, in a specific embodiment, the severance of the wire 36 will take place approximately microseconds following firing of the primer, and the bridging of the contacts 58 will take place approximately 10 microseconds later. The sealed construction of the switch makes it suitable for use in environments having wide ranges in temperature and humidity and the rugged construction of the switch enables it to withstand extreme forces due to vibration or acceleration. The switch may be manufactured in very small sizes, for example 1/2 inch long and 3/8 inch diameter, for use in devices wherein space is at a premium. Further the switch is relatively simple and economical to fabricate and assemble and will provide failure-proof operation even after prolonged storage.

I claim:

1. A fast acting electric switch comprising means forming an explosion chamber, an explosive charge in the chamber, means to ignite the explosive charge, a plunger in the chamber, an electrically conductive face on the plunger, a frangible wire extending transversely of the chamber for severance by the plunger when the explosive charge is ignited, and a pair of electrical contacts located for engagement by the face of the plunger.

2. A fast acting electric switch comprising a cylinder forming an explosion chamber, an explosive charge in the chamber, means to ignite the explosive charge including an ignition wire extending outwardly from the cylinder, a non-metallic plunger in the chamber and slidable axially therein, a metal conductive face on the end of the plunger opposite from the explosive charge, a frangible wire extending across the chamber adjacent said conductive face and adapted to be severed by the plunger when the exposive charge is ignited, and a pair of electrical contacts in the cylinder spaced from said References Cited in theiile of this patent UNITED STATES PATENTS Jennings Jan. 11, 1938 Busacher et. al. Jan. 4, 1949 4 McFarlin July 3, 1951 Kiel July 5, 1955 Bleakney et al July 12, 1955 Filbert Oct. 18, 1955 Schultz et al. July 16, 1957 Daudelin Dec. 10, 1957 Atkins May 20, 1958 Erk et al Nov. 18, 1958 

